How many Devil Pieces a body could accommodate was a direct measure of that person's innate strength—and their potential.
Among these pieces, there also existed a rare anomaly known as "mutated pieces." These were irregular variants, and each one carried the value of two normal pieces.
But whether a set contained a mutated piece was entirely up to chance. Some high-class devils might not have a single one in their entire set, while others could possess several.
Regardless of whether the target had once been human or even an angel, once a Devil Piece was used on them, their body would gain demonic attributes. Such beings were known as reincarnated devils.
After the devastating three-way war, the number of pure-blooded devils in the Underworld had dwindled drastically. In order to preserve their race and maintain their power, devils had no choice but to rely on this method to survive.
And with the creation of Devil Pieces, a new form of competition had emerged in the Underworld—
The Rating Game.
Simply put, it was a high-stakes contest between two high-class devils, wagering their honor and assets. The "pieces" in play were none other than the servants they had reincarnated using Devil Pieces.
Though these servants were technically subordinates, once someone was chosen and reincarnated, their fates became intertwined. From that point on, they shared glory and ruin alike.
As a result, some devils and their servants—though unrelated by blood—formed bonds even stronger than family.
Of course, there were still many old noble houses in the Underworld that looked down on reincarnated devils.
Rias herself belonged to the younger generation of devils. She hadn't even participated in a Rating Game yet, and still had quite a few unused pieces.
But the young heiress was ambitious.
Her goal was nothing less than becoming the strongest champion of the Rating Games in the entire Underworld.
She knew she couldn't surpass the Demon Kings through her own individual strength alone—but if she could gather the strongest possible peerage, then defeating even a Demon King in a Rating Game might not be entirely impossible.
Because of that, unlike other high-class devils who hastily selected servants just to qualify for participation, Rias had always been extremely cautious.
She only chose those she truly got along with.
Looking at Issei Hyoudou—his body continuing to fracture under the strain—Rias hesitated for a moment before finally reaching into her pocket and pulling out a Pawn piece.
Among her unused pieces, she still had a Rook, a Bishop, and a Knight.
But considering that Issei was just an ordinary human, there should have been no need to use a piece with such high magical value.
However—
The moment Rias placed the first Pawn into Issei's body, she froze.
The magic contained within the piece vanished as if swallowed by an endless void.
One Pawn… wasn't enough.
Frowning, she quickly took out a second Pawn.
But soon, she realized the result was almost identical to the first.
Rias stared in disbelief.
At this point, she had no choice but to continue. She had already used two pieces—there was no turning back now.
So the third… the fourth… the fifth…
As more pieces were infused into Issei's body, Rias's expression gradually became numb.
Until finally—
When she inserted the eighth and last Pawn—
Issei's body stabilized.
The cracks disappeared. His breathing steadied.
And at last, he began his transformation into a devil.
"…Eight Pawns…?"
Rias muttered under her breath, her voice tinged with disbelief.
For an ordinary human to require all eight Pawn pieces to reincarnate…
That far exceeded the value of a Knight or even a Rook—
It was already comparable to a Queen.
While each type of Devil Piece represented a different role, the actual amount of magic contained within them wasn't fixed. It depended entirely on the magical power of the King who owned them.
For example, a Pawn belonging to a Demon King could easily rival the magical output of Rias's Rook—or even her Queen.
And yet, even among the younger generation of devils, Rias's magical power was considered exceptional.
Despite that—
Reincarnating Issei Hyoudou had consumed all eight of her Pawn pieces.
There were only two plausible explanations:
Either Issei himself wasn't an ordinary human…
Or he possessed an extraordinarily powerful Sacred Gear, greatly increasing his "value."
With the fallen angel Raynare already dead at Ren Kuroda's hands, and Issei's situation resolved, Ren had originally intended to question Rias and Akeno about a few things.
But just then—
His phone suddenly rang.
The caller was Kokonoe.
The little fox girl's voice on the other end was on the verge of tears—panicked, urgent, and trembling.
Given everything that had happened tonight, Ren's expression sharpened instantly.
There was no way he could ignore the possibility that she had been targeted by a devil or a fallen angel.
After giving Rias and Akeno's school uniforms a quick, assessing glance—as if committing them to memory—Ren stomped the ground.
Boom.
The earth beneath his foot shattered, forming a small crater.
And in the next instant—
His body vanished.
Breaking the sound barrier, he shot off into the distance, leaving behind a stunned Rias and Akeno.
"…Just what is he?" Rias muttered, biting her fingernail, her expression grave. "From his aura, he should be human… but someone that powerful entering our territory without us noticing…?"
Too many things had happened tonight.
Even now, her mind was still struggling to catch up.
Akeno, standing beside her, glanced at Issei—now their newly reincarnated companion.
"That new 'colleague' lying there… he's also a student at our school, right?"
She smiled faintly.
"And now he's your servant. Since he and that man seem to know each other… perhaps we can ask him?"
—
Meanwhile, Ren raced home at blinding speed, wind howling past him like a storm.
The moment he arrived, he rushed inside—
And found Kokonoe.
The little fox girl was curled up on his bed, her entire body hidden beneath the blanket—only a pair of fluffy fox ears poking out.
At the sound of someone entering, those ears twitched slightly.
Then, catching Ren's familiar scent, she slowly pulled the blanket down.
Seeing that she was unharmed, Ren let out a long breath of relief.
His sharp gaze immediately swept across the room.
No signs of a struggle.
No traces of intrusion.
Everything was exactly as he had left it.
"…So," Ren said, crossing his arms, his tone turning flat, "you called me back in such a panic… for what, exactly?"
He narrowed his eyes at her.
"Kokonoe, if you don't give me a very good explanation… I might just pack you up and send you straight back to Kyoto."
The moment she heard that, Kokonoe panicked.
"No way!"
She immediately threw off the blanket and jumped up in protest.
On her very first day at school, her adorable appearance—and her status as a transfer student—had quickly earned her a group of new friends.
It was something she had never experienced back in Kyoto.
There was no way she was going back.
But—
A second after she leapt out of bed—
Ren froze.
Completely.
Because while Kokonoe's upper body was properly dressed in her pajamas…
Her lower half—
Had absolutely nothing on.